1. Field of the Invention
The present invention relates to powering cordless or portable power tools and personal electronics including powering hand tools and electronics, and further including powering such tools and personal electronics items where the power pack and the item are carried on the person.
2. Background Information
Cordless power tools, electronics, and portable electronics that are carried on the person have become increasingly popular. Cell phones, portable radios, laptops, stand alone computers, music and video players and recorders, personal electronic organizers, games and cordless power tools (herein defined as personal items) are evident on the street, in the home, at work, at schoolxe2x80x94virtually in any environment and such items are being used by virtually all segments of the population. However, powering these portable items suffer from the types of power packs presently available. Basically, there are two different types of systems presently available. First, a battery (either rechargeable or not) assembly packaged with the item, secondly, a separate motor combined with a generator. Each of these approaches has limitations.
First, the battery packs for tools are heavy, have limited power, and short duration (in normal use, after one hour or so the battery pack needs to be removed and recharged). An example of a readily available battery pack for such items is the re-chargeable 19.2 volt battery pack from Panasonic that contains 3 amp-HR battery cell types. The pack is configured with 16 cells powering the tool and 16 on a battery charger. The weight of the 16 cells is about 1 Kg, the peak power ranges from about 200-400 watts, the total energy available is about 50 Watt-hours, and is typically used for about an hour before needing to be recharged.
Batteries contained in laptops and in music and video players are marginally acceptable depending on power requirements, while the batteries in personal organizers and games are commercially practical since these items at this time are power efficient. However, it is expected that as more complex games and more complex organizers with higher performance come on the market, increases in battery technology, including rechargeable batteries, will not keep up with the higher power for longer time periods that these new items are likely to require.
Second, fuel-powered generators for tools are heavy, noisy, not very portable, and therefore impractical in many applications. It is common in field construction to see a large generator on the ground and connected by a cord, often tens of feet long, to the tool. These generators are made up of two distinct components, a motor (to provide mechanical power) and an alternator coupled by a shaft to the motor, to convert the mechanical energy into electrical. However, the handy-man homeowner will not purchase such systems for the incidental repairs around the house. These prior art generators are large because, that while the average power is not high (less than 50 watts), the peak power is many times larger while the tool is actually operating. Another prior art solution attaches a motor directly to the tool, for example a chain saw or lawn mower. But again, this arrangement is impractical for smaller tools, and it is out of the question for personal electronic items.
A possible third approach derives from automotive technology, where a engine generator charges batteries in a xe2x80x9chybridxe2x80x9d vehicle. However, such components (engine generator and batteries) are many hundreds of times larger than a tool or electronic item, and do not scale down well. This combination is not found in practice.
It is an object of the present invention to overcome the above limitations and provide a practical power pack for cordless power tools and personal electronics.
The objects set forth above, as well as further and other objects and advantages of the present invention, are achieved by the embodiments of the invention described hereinbelow.
A power pack is constructed with a fuel supply and an integrated motor/alternator that burns the fuel and supplies an electrical power output. That output is rectified and controlled to provide a direct current (DC) electrical output that provides power to both a load and to an energy storage assembly. That energy storage assembly is rechargeable batteries and/or capacitors in a preferred embodiment. The batteries and/or capacitors supply the peak power requirements of the load, and the integrated motor/generator provides the average power to the load and the storage assembly. A key enabler is a very small, light-weight generator made up of a fully-integrated motor and alternator and the recognition that this integrated motor /alternator could, in combination with energy storage, lead to a practical fuel-powered power pack with many advantages over existing ones.
In an embodiment the fuel supply and integrated motor/alternator may be formed as one or two modules connected by a fuel lineThe integrated motor/generator module may then be connected via an electrical cable to a second module containing the battery/capacitor pack and the electronics. The item being powered may be connected via another electrical cable to the second module. For example, the integrated motor/alternator may be placed on the floor, the electronics and batteries placed on a desk along side of a computer or game module that is being powered. In another embodiment, the fuel/integrated motor/generator and electronics/battery/capacitors are carried on a user""s person while the item being powered may be an audio/video device worn on the head of the user. The audio device may be a cell phone or a player or some type of game device.
For a better understanding of the present invention together with other and further objects thereof, reference is made to the accompanying drawings and detailed descriptions, and its scope will be pointed out in the appended claims.